U.S. Pat. No. 3,101,418, which issued Aug. 20, 1963, and which is assigned to the present assignee, discloses an electric programming unit which is intended to control electrical equipment, such as the solenoid valves of an automatic lawn sprinkling system, on a pre-programmed basis. The unit described in the patent may be set to turn each of a plurality of different valves of the sprinkling system on and off at predetermined times each day. The unit described in the patent also includes a skip-a-day control which is actuated during pre-established 24 hour periods, so that the controlled equipment may remain inactive throughout pre-selected days.
The programmed controller of the present invention is of the same general type as that described in the aforesaid patent, and it may be used for the same purposes. However, the controller of the invention has certain advantages over the unit described in the patent, since it is of a simpler construction. Moreover, the controller of the present invention is more flexible than the controller of the patent, in that it can be set to control a relatively large number of different pieces of electrical equipment, independently of one another, and in that it may be used to turn as required, and over a relatively large number of days, all on a pre-programmed basis.
The present invention, like the controller of the patent, finds particular utility in controlling automatic lawn sprinkler systems, and it serves, for example, to control the times at which different sections of a particular lawn sprinkler system are to be turned on and off during each day, and over, for example, a 28 day interval. However, it will become evident as the description proceeds that the programmed controller of the present invention finds general utility in controlling a variety of electrically energized systems and units, which are to be selectively controlled so as to be turned on and off at predetermined times, and in accordance with pre-established programs. For example, the programmed control unit of the invention may be used to control factory lighting, traffic lights, electrically controlled machine tools, electrically actuated doors, and so on.
A feature of the programmed control unit of the invention, in addition to the flexibility and range of its programmed control functions, is that it is inherently simple to construct, relatively inexpensive to manufacture, and in that it may be easily and conveniently installed and programmed for a wide variety of uses, as set forth above. Another feature of the programmed control unit of the invention is its capability of providing long periods of trouble-free operation, and in that it may be easily serviced, as required.
The particular programmed control unit to be described herein includes two program storage members which, in the specific embodiment to be described, take the form of an endless belt and a drum, respectively. The two storage members are driven at a timed speed by a clock motor which is also included in the unit. However, other equivalent storage members, such as magnetic tapes, magnetic discs, or the like, may be used, as will become evident as the description proceeds.
Each program storage member in the unit to be described, is divided into separate channels, and a different channel on each storage member is used to operate on an independent basis, each of the associated pieces of equipment which are to be controlled by the programmed control unit. The individual channels may contain, for example, electrically conductive and non-conductive segments, and each channel may be sensed by a pair of stylii, with an electrical connection being established across the stylii of each pair whenever a conductive segment of encountered.
In the particular unit to be described, the endless belt storage member is divided into hours and minutes on a 24 hour basis. Each channel on the belt contains conductive and non-conductive segments which establish the times at which each piece of associated equipment is to be turned on and off during each day. The drum storage member has the same number of channels as the belt, and each channel is divided into, for example, two sections, respectively representing morning and afternoon, for each of 28 days. The channels on the drum also contain electrically conductive and non-conductive segments, so that the control by the belt may be superseded by the drum for any day, either in the morning or afternoon, or both.
By virtue of the program storage members discussed, the programmed control unit of the invention is capable of single or multiple channel control of associated pieces of electrical equipment, either for a predetermined program period, or on a repeat cycle mode of operation. The control unit of the invention provides that the different pieces of controlled electrical equipment are switched on and off in accordance with predetermined independent schedules.
The program storage members used in the unit of the invention may take the form of a magnetic tape, belt, drum, disc, or any other suitable form and they may be either single channel or multiple channel. Conductive segments may be formed in the individual channels of the storage members, for example, by a conductive coating, such as conductive paint or graphite, or they may be formed by pieces of conductive tape with a pressure-sensitive adhesive backing. Alternately, the belt may be formed of a conductive material, and programming may then be accomplished by forming insulated areas on the conductive material where the electrical output is not desired. An appropriate adhesive tape, for example, may be used for this purpose.
Other types of program storage members with appropriate transducers may be used. These may include, for example, magnetic tapes, drums or discs, punched tapes, optical recording mediums, and so on. When the aforesaid conductive segment type of storage members are used, the associated sensing stylii are connected to electronic trigger gates, for example, so that low current is maintained through the stylii to minimize arcing, and the triggered gates provide the relatively high switching currents required for controlling the associated equipment.
As mentioned above, the control unit of the invention may be used to control a wide variety of pieces of electrical equipment on a scheduled basis, independently of one another. The control schedule is extremely flexible. The unit may be constructed so that the belt, for example, is easily removable and replaceable, so that control programs may be changed at will. This latter feature is especially desirable in lawn sprinkling systems, for example, for summer and winter sprinkling.